Hey Derick.
Very good question! The most important thing you wanna do before engaging in all the 'content' so to speak, is to surround yourself with Japanese. Listen to music (even though it's horrible haha), watch movies/series, listen to podcasts (learning and native, even though you don't understand what they are saying) and put post it notes all around your room with Japanese words.
A good rule of thumb is, when you are taking a shower and close your eyes, all you hear is Japanese words and sentences. THEN you know your mind is optimized for absorbing new knowledge.
When that is done the setting for the real studying is perfect. You wanna start learning about the structure of the language. This means getting to know all the weird grammar stuff that makes Japanese sooo different (and interesting) from European languages. I see you already know about particles - perfect. Find a good text book / grammar book and get going. While doing that, on the side line you should always be learning new vocabulary and (if you want) kanji. It's important that when learning new words, you review them somehow. If you wanna make your own flashcards or use a software is up to you (I personally use my Iphone so I can review words and kanji everywhere whenever I have time).
Of course there is a natural order in which you should learn the grammar and instead of figuring it out by yourself, you should find a grammar book or textbook that's organized in a way that's effective for learning. This mean, don't by a grammar dictionary! It's useless unless you already know the grammar that's in it.
Last but not least, use what you've learnt! If you don't have penpals or real life friends who speak Japanese, go post examples of what you've learnt here and get feedback or just write sentences down or say them aloud for yourself.
Find exercises and do loads of them. The more you use what you've learnt the better and please remember: Always review! If you don't you will have forgotten everything you learn in two weeks time.
Hope this helps =)
